I was digging thru some old parts on my shelf today, and pulled out a chrome single groove crank pullley and balancer. These parts were on a '67 302 I bought in 1971 or 72. The pulley had been chromed, but is now dirty, greasy, and beginning to surface rust. I saw a pn on the pulley, so I cleaned it up, and found the number was '3858533 BJ'. Doing some digging I found this number is associated wtih the '67-68 Z28 and perhaps a few other SHP small block chevy engines in the mid 60's. The issue is that it is listed as a 2-groove pulley on CRG, but the one I have is a single groove. Is there any possible explanation for this that I'm not thinking of?

That's the correct part number for that application but it should be a two-groove pulley. I suppose somebody trimmed off the outer groove? That's all I can think of. Maybe if you posted a picture or two, that would help in figuring it out.

That's the correct part number for that application but it should be a two-groove pulley. I suppose somebody trimmed off the outer groove? That's all I can think of. Maybe if you posted a picture or two, that would help in figuring it out.

Hi Jon, I'm attaching a few photos I took this morning. If it's been machined or modified (other than the chroming), it's not obvious to me. This pulley was on a '67 302 I bought from Paul Vanderley (NHRA HOF racer/machinist) in late '71 or early '72; the engine came from a '67 Z28 that Paul had purchased from Jack Cooley, who drag raced the Z28 in the late 60's/to about '71 or so. I don't have a 2-groove version to compare this with, but I'd be very interested in your thoughts if it's possible to machine a 2-groove to this point? (I had to change to a new topic, as the first time I tried to post this it was 6kb over the 400 limit; and once you hit that, you can't modify and repeat!

Thanks for the photos, Gary. Somebody sure did a nice job modifying it. Like you say, nothing looks blatantly obvious but I'll try and look at my originals later tonight to see if I can spot what may have been done.

Our discussion on the pulley prompted me to call Jack Cooley; I've had his contact information for awhile now, but haven't talked to him until today. He didn't recall the pulley or doing any machining on it, but the engine was modified when I purchased it (as far as they could go in the stock classes at the time). Jack told me he is 87 yrs old (on 10 Jan this year), so anything he remembers is great.. I had heard that he bought the car from Dickie Hairrel, but he told me that wasn't correct; he bought it direct from Chevrolet (one of the earliest '67 Z28s). By 1971, he was running under the national record in his 'stock' class (11.6's) with the high revving 302!

Prior to the 67 Z, he raced a '63 Z11 aluminum bodied Chevrolet which he also purchased new from Chevrolet in '63!

When I purchased the 302 (short block only) it was 0.030" over, running Forgedtrue pistons (teflon guides in the skirts), Dykes rings, and the pistons were running right to the top of the deck and to the valves - there was light carbon on the top of the pistons, EXCEPT for where the valves opened, and a 1/8" ring around the piston top where it *touched* the head or gasket when TDC! The deck had been milled to the point that the stamped numbers were gone. Supposedly the stock crank and rods had had the 'DynaRev' treatment from Hank the Crank (of the Crank Shaft Co) at the time. The cam was a Lunati, blueprinted to the '67 Z28 specs. I isntalled 202 valve FI heads and a Tarantula intake and homemade headers in my Henry J.. What I recall is when that engine revved, it sent waves of adrenaline thru my body! I can still feel it..

Looked at my original 1968 3858533 BJ and it looks exactly like the photo with the exception of the missing outside groove. After looking at my pulley, I can see where it would be real easy to machine the outer groove off. It also appears that they left a little too much metal around the outer edge.....they could have machined a little more off of the edge that protrudes out toward the front.

Can you post pix of your original pulley for comparison purposes? I suppose I could see machining off one pulley groove if that gave them some kind of advantage drag racing.. but it seems a lot of trouble even for that? This pulley supposed came from one of the early '67 Z28 engines, but I think the same PN may have been used on earlier SHP engines as well?

I looked at a couple of my old pulleys tonight and agree with Jerry that it looks like yours just has the outer groove removed. There is a slight ridge or parting line in between the two grooves on my pulleys and that seems to be about where yours has been machined to. I don't have time to get pictures of that tonight but maybe over the weekend.

I looked at a couple of my old pulleys tonight and agree with Jerry that it looks like yours just has the outer groove removed. There is a slight ridge or parting line in between the two grooves on my pulleys and that seems to be about where yours has been machined to. I don't have time to get pictures of that tonight but maybe over the weekend.

X2....on the parting line and also getting pictures tonight. Will have time tomorrow afternoon for the pictures.

Could it have had something to do with balancing the rolling assembly? I have saw some weird things go on back in the day trying to get balance dead on. I mean down too grinding bolt heads and things like that. So..........